Altoid tin etching tutorial

Eminent steampunker [Jake Von Slatt] wrote a small article on etching candy tins for The Steampunk Bible, but the limited space available in the book didn’t allow for a full exposition. To make amends for his incomplete tutorial, he posted this walk through to compliment the Bible’s article.

The process is very similar to the manytutorials we’ve seen on home-etching PCBs using the toner transfer method. Removing the paint from the Altoid tin, creating a mask, printing it on the Sunday circulars, and taking an iron to the tin is old hat for home fabbers.

Unlike PCB manufacturing, [Mr. Von Slatt] doesn’t bother with Ferric Chloride or other nasty chemicals – he does everything with electrolysis. After adding a few tablespoons of table salt to a bucket of water, [Jake] takes a DC power supply and connects the positive lead to the lid and the negative lead to the base. a bit of electrical tape around the corners of the lid keeps the metal from getting too thin.

A nice Copper finish can be applied to a finished tin by swabbing on a solution of Copper Sulfate – a common ingredient in “Root Kill” products. Of course that’s not a necessary step; you can easily enjoy and elegant Altoid tin bare metal.

But maybe you can design the PCB in such way that it will get etched from middle to edges (eg.: thick distance to be etched between traces around middle of PCB, thin by the edges). I also guess that you can place the free electrode (the one not directly attached to PCB) near the middle of PCB, therefore the current will preffer shortest path (with lowest resistance) and will start to etch the PCB from the middle.

It also doesn’t have to be from middle to edges, you can etch the PCB from one side to another… Maybe this approach will need to experiment a bit with salinity of water… (You may need slightly higher resistance of water to etch more precisely)

“Unlike PCB manufacturing, [Mr. Von Slatt] doesn’t bother with Ferric Chloride or other nasty chemicals – he does everything with electrolysis.”
this is priceless, leftovers from electrolysis is so toxic that it banned to flash it in toilet

What you’ll find in the electrolysis solution at the end is primarily Copper (II) Hydroxide (green residue), smaller amounts of Cu[(H2O)6]2+, and tiny amounts of Cupric Chloride (yellow residue).

Most juristictions frown on disposal of heavy metal solutions.

All that being said, a little reading into other examples of this technique did spit out the following:

“Secondly, Disposal of copper waste is not an issue. The oxides/hydroxides can be dissolved in diluted muriatic acid, vinegar, or battery acid and an aluminum wire is added until a clear solution is obtained. This can be decanted down the drain as it simular to deodorant (aluminum chloride) or baking alum(aluminum sulfate). The pinkish copper grains can be mixed with saw dust, oats, flour or any organic that chars black and borax and melted with a propane flame to get copper metal for later use.”

Additionally, it can produce tiny amounts of Hydrogen and Chlorine gas. It will likely be in small enough amounts to not be an issue, but still: ventilate, ventilate, ventilate.

Weeelll, when using copper sulfate to etch copper or brass there is no left-over solution, I’m still using essentially the same batch I mixed up 5 years ago. I add more water and copper sulfate as needed.

In the case of the ‘tins’ we are talking about salt water, tin, and iron; none are particularly dangerous.

Now, stainless steel containing chromium and anything chrome plated should not be etched in this way as the byproducts of that are VERY nasty.

Won’t the copper disappear and corrode over a month or two? I once tried electroplating a nickel with copper, and that is what happened for me, because nickel is higher on the reactivity series than copper. My grandparents had a similar problem with a shower drainage fixture corroding away because of dissimilar metals.

Does anyone have a way of circumventing this? (Not the shower – the copper plating)

I have found it easier to use discarded label sheets that have the release coating. I use the Avery return address labels and save the release sheet. Laser print directly on this sheet and iron as usual, except: Don’t move the iron around as it will smear the toner. Just use gentle uniform pressure and let it cool completely. It works every time.